Flexible attachment plug cap with strain relief



July 7, 1936 R. G. BENNETT FLEXIBLE ATTACHMENT PLUG CAP WITH STRAIN RELIEF Filed Jan. 6, 1934 INVENTOR ROSS G. BENNETT B Y ms ATTORNEYS mated July 7, 1936 UNITED STATES PATENT OFFICE.

FLEXIBLE ATTACHMENT PLUG car WITH STRAIN RELIEF Ross G. Bennett, Fairiield, Conn assignor to L v The Bryant Electric Company, Bridgeport, P Conn., a corporation of Connecticut Application January 6, 1934, Serial No. 105,589

4 Claims.

This invention relates to attachment plug caps. More particularly it relates to attachment plug caps made of flexible insulating material such as soft rubber and provided with means for reliev- 5.-ing strain put upon the contacts'by the usual feedwires.

' It is an object of this invention to provide a plug cap of this type with improved means for relieving the strain-of the feed wires upon the 10 wire terminals of the prong contacts.

Another object is to provide strain-relief means to which the feed wires may be quickly connected after the wires have been connected to the wire terminals of the plugs contact prongs and which 15 will hold the feed wires in an-efiective manner.

Other objects and advantages of my invention will appearas it is described in connection with the accompanying drawing:-

1 In the drawing:--

20 Figure 1 is a vertical mid-section view through the outside casing of an attachment plug cap constructed according to the principles of my invention.

. Figure 2 is .aplan view of the contact carrying 25 disc used in my invention.

Figure 3 is an elevation view of the contact carrying disc shown in Figure 2.

Referring to the drawing, the attachment plug cap comprises a tubular outside casing It! made 30 of insulating material such as soft rubber. This casing is larger at one end than the other and e is substantially cylindrical at the large endand tapers into a reduced 'neck'llld at the small end, through which neck the conductor cord 12 con- 35 taining feed wires lband l6 may pass. The reducedne k Illa of the casing provides convenient means anyone to grasp the plug for the purpose of connecting it to or disconnecting it from an attachment plug or receptacle. The large end to of the casing ill is provided interiorly with an 'annular groove H which is adapted to receive a flange i3 upon a disc l5 whose diameter is substantially that of the interior diameter ofthe large end of the casing. The disc I 5 maybe made 45 of rubber and be sufficiently thick to give substantial rigidity to it. Due to the flexibility of the casing I the disc 15 can be inserted into the large end of the casing l0 and removed therefrom by flexing the casing as required. Upon the 50 inner face of the disc l there is formed integrally with the disc, a barrier I'I which serves to divide the interior of the casing it) into two chambers when the disc is in place as shown in Figure 1. The barrier is preferably thinner than the disc 55 and may be subjected to limited flexing or bend-' ing. "symmetrically placed at each side of the barrier II are conventional attachment plug contact prongs l8 and I8 which are each provided at one end with a. wire terminal as Ida and lfla. Slits are provided in the disc l5 for the accommo- 5 dation of prongs l8 and I9, the size of the slits being regulated so that when the prongs are inserted therein they will be frictionally held there bythe friction between the sides of the slits and the prongs. 10 Attachment plug caps as just describedhave heretofore been known. The novel features of my invention will now be described. According to common practice the feed wires it and it of the conductor cable I! are secured to the wire terminals l8a and Isa. In order to relieve these wire terminals of strain which is incident to the disconnection of the cap from an attachment plug or receptacle by a person grasping the cable and jerking it, I provide apertures in the barrier I! through which the feed wires i4 and i6 may pass in opposite directions in connecting each with one of the wire terminals Ida and Na. In order that the feed wires l4 and it need not be threaded through the aperturesI form the apertures with an enlarged inner portion of approximately the same cross sectional area as the cross sectional area of the feed wires and I provide slots 20a and lid leading from said apertures to the sides of the barrier fll. Since the barrier is made of flexible material and is sumciently thin to permit flexing, the size of the slots 20a and 2 la may be temporarily enlarged by bending up those portions of the barrier which are above the slots so that the feed wires it and it may be inserted into the apertures-til and ii sidewise through the slots. 'The flexibility of the barrier also makes possible the placing into the apertures of wires whose cross sectional area is larger than the normal area of the apertures. 40

In order to prevent flexing of the barrier when the disc I5 is inserted in assembled position as shown in Figure 1, the contour of the barrier is made to corresponding in a general way with the interior contour of the casing It, at the part of the casing to which the barrier is adjacent. The engagement of the edge of the barrier with the I inside surface of the casing Ill will maintain the edges of the apertures 20 and}! to grip the feed wires l4 and ii to insure that the stress of the conductor cord I! shall be transmitted to the barrier I'I.

Thus it will be seen that I havelprovideda simple and convenent means for engaging feed wires with a strain relief member to relieve the wire terminals of the contact prongs of an attachment plug cap of any strain that is put on the feed wires, and this means does not require threading of the wires through apertures in a. strain relief member. At the same time I have provided an effective means to cause the strain relief member to grip the feed wires to make more certain of the transmission of any strain of the conducor cord to the strain relief member.

By my invention the feed wires may be engaged with the strain relief member either before or after they are fastened to the wire terminals.

Modifications and changes in form within the scope of my invention will occur to those skilled in the art therefore I do not limit my invention to the specific form of the invention as illustrated in the drawing.

1 claim:--

1. An attachment plug cap comprising a casing formed of elastic insulating material, a disc engaged with one end of said casing, prong contacts carried by said disc and having wire terminals on their inner ends, a flexible strain relief member formed integral with said disc and positioned between said wire terminals, said strain relief member being provided with apertures which are connected by slots to the outside edges of said member whereby feed wires may be inserted in said apertures sidewise after the ends of said wires have been connected to said wire terminals, the edges of said apertures exerting a clamping action on said feed wires, and the edges of said barrier engaging with the inside walls of said casing to maintain said clamping action.

2. An attachment plug cap comprising a hollow casing member, a discmember in engagement with one end of said casing member, at least one of said members being elastic to permit distortion thereof during the joining together of said members, prong contacts carried by said disc member, a flexible strain relief member secured upon the inner face of said disc member and having apertures for the accommodation of feed wires of a conductor cable, said apertures extending to the outside edge of said strain relief member to permit a portion of said strain relief member to be turned back for the insertion of feed wires after the feed wires have been connected to said contacts, the edges of said apertures exerting a 5 clamping action on said feed wires, and the edges of said barrier engaging with the inside walls of said casing to maintain said clamping action.

3. An attachment plug cap comprising a hollow casing member, a disc member in engagement with one end of said casing member, at least one of said members being elastic to permit distortion thereof during the joining together of said members, prong contacts carried by said disc member, a flexible strain relief member secured upon the inner face of said disc member and having apertures for the accommodation of the feed wires of a conductor cable and of less width thanv the diameter of the feed wires, said apertures extending to the outside edge of said strain relief member to permit a portion of said strain relief member to be turned back for the insertion of the feed wires after the feed wires have been connected to said contacts, said strain relief member having its edges in engagement with the inner walls of said casing member when in assembled position.

4. An attachment plug cap comprising a casing of insulating material, a disc positioned in one end'thereof, prong contacts carried by said disc and having wiredzerminals at their ends, a flexible barrier secured on said disc adapted to be engaged by feed wires and to receive strain therefrom, said barrier being positioned between said wire terminals and having apertures extending to the outside edge thereof whereby feed wires may be inserted in said aperture after said wires have been connected to saidwire terminals, the edges of said apertures exerting a clamping action on said feed wires, and the edges of said barrier engaging with the inside walls of said casing to maintain said clamping action.

ROSS G. BENNETT. 

